I saw him going to market. (Compoud)

Explanation:

Correct Answer is: I saw him and he was going to market
• Compound sentence এ দুই বা ততোধিক principal clause বা co-ordinate clause থাকে।
এছাড়া Compound sentence এ সাধারণত and, or, but, yet, so, therefore, otherwise, else, both — and , either — or , neither — nor, not only — but also ইত্যাদি co-ordinating conjunction দ্বারা দুইটি principal clause যুক্ত থাকে।

অপশনে উল্লেখিত sentence গুলোর মধ্যে কেবল মাত্র – I saw him and he was going to market -বাক্যটিতে দুইটি clause রয়েছে এবং and দ্বারা যুক্ত হয়েছে।
তাই সঠিক compound sentence – I saw him and he was going to market